Synergistic vulcanizates of poly-carboranylenesiloxane polymers

ABSTRACT

A synergistic vulcanizate is prepared by covulcanizing polycarboranylenesiloxane polymers having recurring structural units of the following formulas:

United States Patent 19 Larchar, Sr. et al.

[451 May 13, 1975 SYNERGISTIC VULCANIZATES 0F POLY-CARBORANYLENESILOXANE POLYMERS [56] Reierences Cited UNITED STATES PATENTS 3,388,092 6/1968 Heying et al. 260/465 E 3,463,80l 8/l969 Papetti et al. 260/465 E 3,637,589 l/l972 Kwasnik et 260/465 E Primary Examiner-Wilbert J. Briggs, Sr. Attorney, Agent, or Firm-Thomas P. ODay; Donald F. Clements; F. A. lskander [57] ABSTRACT A synergistic vulcanizate is prepared by covulcanizing poly-carboranylenesiloxane polymers having recurring structural units of the following formulas:

CH CH H3 Si- CB1QH1QC Si O Sl- O Si--- 0 [75] Inventors: Trescott B. Larchar, Sr., Hamden; Robert N. Scott, Wallingford, both of Conn.

[73] Assignee: Olin Corporation, New Haven,

Conn.

[22] Filed: Oct. 1, 1973 [21] Appl. No.: 402,443

[52] US. Cl. 260/825; 260/2 M; 260/37 SB; 260/465 E; 260/465 G I CH3 CH3 N 81 CB1OH1 0C Si I I l l CH3 CH3 [5 1] Int. Cl C08g 47/02 [58] Field of Search 260/825. 46.5 E

l l l CH3 CH3 CH3 and CH3 CH3 CH3 O Si 0 Si S1-- O CH3 C 115 3 7 Claims, No Drawings SYNERGISTIC VULCANIZATES OF POLY-CARBORANYLENESILOXANE POLYMERS The invention herein described was made in the course of or under a contract or subcontract thereunder, with the Department of the Navy.

This invention relates to synergistic vulcanizates of selected poly-carboranylenesiloxane polymers. More particularly, the vulcanizates of this invention are prepared by covulcanizing poly-carboranylenesiloxane polymers having recurring units of the following structural formulas:

Henceforth in this application the above-noted formulas will be referred to by the shorthand symbols A and B as shown above. The chemical name for polymer A is poly [1-dimethylsilyl,7-(hexamethyltrisiloxanyl)- 1,7-dicarbaclosododecaborane] and for polymer B is poly l-dimethylsilyl,7-(S-phenyl- 1,1 ,3,3,5,7,7- heptamethyltetrasiloxanyl)-1,7- dicarbaclosododecaborane Previous attempts to prepare vulcanizates of polymers A or B individually have generally proven unsuccessful. The polymer A was vulcanized using standard techniques, however, tackiness and occasional bubbling were noted in the resulting vulcanizates. The polymer B could not be vulcanized using standard techniques.

Now it has been found in accordance with this invention that vulcanizates of selected mixtures of polymers A and B resulted in surprising and synergistic improvement in the properties of the prepared product. The vulcanizates of this invention had higher ultimate tensile strength and percent elongation and also had improved resistance to both air oxidation and reversion in' vacuum. While it is further noted that extrusion techniques could now be used on the prepared covulcanizates it was also noted that tackiness and bubbling in the resulting product were eliminated.

The surprising and advantageous properties shown by the vulcanizates of this invention are disclosed in the Examples. Examples V and V1 show the problems asso- 6 ciated with attempts to vulcanize either polymer A or B alone. The remaining Examples (1 to IV) show the as disclosed in US. Pat. No. 3,637,589. It is further noted that the radicalCB l-l, C- as shown above in formulas A and B and throughout the remainder of this application is intended to mean the meta or the para carborane structure as shown for example in US. Pat. No. 3,397,221. This 221 patent additionally shows another method of preparing the polymers A and B.

The covulcanization procedure used in preparing the vulcanizates of this invention consists of mixing the components on a rubber mill followed by curing under pressure at elevated temperature using organic peroxide curing agents. Other variations of this standard procedure may also be used.

The recurring units of polymers A and B may have varying molecular weights. More particularly, polymer A may have a molecular weight of from about 16,000 to about 120,000 or higher and preferably from about 80,000 to about 120,000. Polymer B may have a molecular weight of from about 8,000 to about 20,000 or higher and preferably from about 12,000 to about 16,000. The phenyl group in polymer B may contain substituents such as alkyl, alkoxy and trifluoroalkyl of up to three carbon atoms if desired.

While the carborane structure may be meta or para as indicated above, the meta structure is preferred.

The proportions of polymer A and B used in preparing the covulcanizates of this invention may generally vary from about 1:20 to about 121.67 parts of polymer B to parts of polymer A by weight. Preferably, the amounts ofpolymers B and A used will vary from about 1:10 to about 1:2.5 and even more preferably about 1:5

parts of polymer B to parts of polymer A by weight will It was further observed that the prepared vulcanizate showed no signs of tackiness or bubbling.

EXAMPLE III A vulcanizate was prepared using the same procedure followed in Example I except that 1.53 gms (30 parts by weight) of polymer B was used. Results were examples as follows:

EXAMPLE l 10 The following components were mixed in a rubber Tensile (Psi) mill: Initial 390 Postcured in Air 415 Vacuum heated 77 w (gms) p by wt 15 Elongation Polymer A 50 I Initial 655 Polymer B 5 1 Postcured in Air 385 Min-U-Si (silica) 4.0 3 Vacuum heated 300 Cab-O-Sil Ms-7 0.75 Hardness (Shore A) (colloidal pyrogenic I Silica pigment) Initial 44 05 I0 Postcured in Air 58 Varox (organic 0.125

peroxide) It was further observed that the prepared vulcanizate showed no signs of tackiness or bubbling.

EXAMPLE IV A vulcanizate was prepared using the same procedure followed in Example I except that 2.01 gms (40 parts by weight) of polymer B was used. Results were The molecular weight of polymer A used was about 94,000 and of polymer 8 was about l2,000. The carbo- 25 rane structure used was the meta carborane.

The mixture was then cured under pressure in a 2 X 2 X A; inch mold for 45 to 48 minutes at 345F. The tensile strength, elongation and hardness properties of the product were determined and then it was postcured o as follows: at 500 F. for 72 hours in air. One portion of the product was further heated at 500F. for 72 hours under vacuum. Property tests were again made and the results Tensile Strength (psi) are as follows:

Initial 335 Postcured in Air 360 Vacuum heated 80 Tensile Strength (psi) Elongation Initial 370 Initial 580 Postcured in Air 400 Postcured in Air 3l5 Vacuum heated reverts (depolymerizes) Vacuum heated 35 Elongation Hardness (Shore A) Initial 6l0 Initial 42 Postcured in Air 350 Postcured in Air 56 Vacuum heated reverts Hardness (Shore A) Initial 40 45 EXAMPLE V Postcurecl in Air 49 An attempt to prepare a vulcanizate was made using the procedure followed in Example I but with no poly- It was further observed that the prepared vulcanizate met B present Results were as follows:

showed no signs of tackiness or bubbling. 50

EXAMPLE 1 Tensile Strength (psi) A vulcanizate was prepared using the same proce- Initial y 225 Postcured in Air 210 dure followed in Example I except that 1.0 gms (20 parts by weight) of polymer B was used Results were Vacuum heated as follows' initial 585 Postcured in Air 280 Vacuum heated reverts Tensile Strength (psi) Hardness (Shore A) Initial 450 Initial .40 Postcurcd in Air 470 Postcured in Air 49 reverts Elongation Vacuum heated It was further observed that the prepared vulcanizate was tacky and bubbles were present.

EXAMPLE VI An attempt to prepare a vulcanizate was made using the procedure followed in Example I except that 5 grns Initial 45 Postcuretl 60 6 100 parts) of polymer B and no polymer A was used. of polymer B to parts of polymer A by weight are used. The product although dimensionally stable was too soft 4. The vulcanizate of claim 1 wherein the molecular to permi measur m nt of physi l properties. weight of polymer A is from about 16,000 to about 120,000 and the molecular weight of polymer B is from What is claimed is: 5 about 8.000 to about 20,000. l. A vulcanizate of a mixture of polycar- 5. The vulcanizate of claim 4 wherein said carborane boranylenesiloxane polymers A and B said polymers structure CB H C in polymers A and B is the having recurring structural units of the formulas: meta structure.

$Ha THE. THE T "*S:l.--CB H C- Ti-O -----Si O --Si-O T13 CH3 CH3 113 CH CH CH (3H (1H si-- 03 111 0 s1 o s1 o $1..-- o -.s1. o

l I l a l CH c113 Lei a CH3 wherein from about 1:20 to about l:1.67 parts of poly- 6. The vulcanizate of claim 5 wherein about l:l0 to mer B to parts of polymer A by weight are used. about 1:25 parts of polymer B to parts of polymer A 2. The vulcanizate of claim 1 wherein about l:l0 to by Weight are usedabout l:2.5 parts of polymer B to parts of polymer A 7. The vulcanizate of claim 6 wherein about 1:5 parts by weight are used. of polymer B to parts of polymer A by weight are used.

* i in it n- 3. The vulcanizate of claim 1 wherein about l:5 parts 

1. A VULCANIZATE OF A MIXTURE OF POLYCARBORANYLENESILOXANE POLYMERS A AND B SAID POLYMERS HAVING RECURRING STRUCTURAL UNITS OF THE FORMULAS:
 2. The vulcanizate of claim 1 wherein about 1:10 to about 1:2.5 parts of polymer B to parts of polymer A by weight are used.
 3. The vulcanizate of claim 1 wherein about 1:5 parts of polymer B to parts of polymer A by weight are used.
 4. The vulcanizate of claim 1 wherein the molecular weight of polymer A is from about 16,000 to about 120,000 and the molecular weight of polymer B is from about 8,000 to about 20,000.
 5. The vulcanizate of claim 4 wherein said carborane structure -CB10H10C- in polymers A and B is the meta structure.
 6. The vulcanizate of claim 5 wherein about 1:10 to about 1:2.5 parts of polymer B to parts of polymer A by weight are used.
 7. The vulcanizate of claim 6 wherein about 1:5 parts of polymer B to parts of polymer A by weight are used. 